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46 International Energy Agency | Special Report
Figure 1.14 ⊳ Global electricity generation by source in the APC
IEA. All rights reserved.
Renewables reach new heights in the APC, rising from just under 30% of electricity supply in 2020 to nearly 70% in 2050, while coal-fired generation steadily declines
Note: Other renewables = geothermal, solar thermal and marine.
2
4
6
8
10
12
14
2010 2020 2030 2040 2050
Thousand TWh
20%
40%
60%
80%
100%
2020 2030 2050
Oil
Unabated natural gas
Unabated coal
Fossil fuels with CCUSHydrogen based
Nuclear
Other renewables
Hydropower
WindSolar PV
Chapter 2 | A global pathway to net-zero CO₂ emissions in 2050 47
Chapter 2
A global pathway to net-zero CO₂ emissions in 2050
The Net‐Zero Emissions by 2050 Scenario (NZE) shows what is needed for the global
energy sector to achieve net‐zero CO2 emissions by 2050. Alongside corresponding
reductions in GHG emissions from outside the energy sector, this is consistent with
limiting the global temperature rise to 1.5 °C without a temperature overshoot (with
a 50% probability). Achieving this would require all governments to increase
ambitions from current Nationally Determined Contributions and net zero pledges.
In the NZE, global energy‐related and industrial process CO2 emissions fall by nearly
40% between 2020 and 2030 and to net zero in 2050. Universal access to sustainable
energy is achieved by 2030. There is a 75% reduction in methane emissions from fossil
fuel use by 2030. These changes take place while the global economy more than
doubles through to 2050 and the global population increases by 2 billion.
Total energy supply falls by 7% between 2020 and 2030 in the NZE and remains at
around this level to 2050. Solar PV and wind become the leading sources of electricity
globally before 2030 and together they provide nearly 70% of global generation in
2050. The traditional use of bioenergy is phased out by 2030.
Coal demand declines by 90% to less than 600 Mtce in 2050, oil declines by 75% to
24 mb/d, and natural gas declines by 55% to 1 750 bcm. The fossil fuels that remain
in 2050 are used in the production of non‐energy goods where the carbon is
embodied in the product (like plastics), in plants with carbon capture, utilisation and
storage (CCUS), and in sectors where low‐emissions technology options are scarce.
Energy efficiency, wind and solar provide around half of emissions savings to 2030 in
the NZE. They continue to deliver emissions reductions beyond 2030, but the period
to 2050 sees increasing electrification, hydrogen use and CCUS deployment, for which
not all technologies are available on the market today, and these provide more than
half of emissions savings between 2030 and 2050. In 2050, there is 1.9 Gt of CO2
removal in the NZE and 520 million tonnes of low‐carbon hydrogen demand.
Behavioural changes by citizens and businesses avoid 1.7 Gt CO2 emissions in 2030,
curb energy demand growth, and facilitate clean energy transitions.
Annual energy sector investment, which averaged USD 2.3 trillion globally in recent
years, jumps to USD 5 trillion by 2030 in the NZE. As a share of global GDP, average
annual energy investment to 2050 in the NZE is around 1% higher than in recent years.
The NZE taps into all opportunities to decarbonise the energy sector, across all fuels
and all technologies. But the path to 2050 has many uncertainties. If behavioural
changes were to be more limited than envisaged in the NZE, or sustainable bioenergy
less available, then the energy transition would be more expensive. A failure to
develop CCUS for fossil fuels could delay or prevent the development of CCUS for
process emissions from cement production and carbon removal technologies, making
it much harder to achieve net‐zero emissions by 2050.
S U M M A R Y
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2.1 Introduction
Achieving a global energy transition that is compatible with the world’s climate goals is
unquestionably a formidable task. As highlighted in Chapter 1, current pledges by
governments to reduce emissions to net zero collectively cover around 70% of today’s global
economic activity and global CO2 emissions. The Announced Pledges Case shows that, if all
those pledges were met in full, it would narrow the gap between where we are heading and
where we need to be to achieve net‐zero emissions by 2050 worldwide. But it also shows
that the gap would remain large. Meeting all existing net zero pledges in full would still leave
22 gigatonnes (Gt) of energy‐related and industrial process CO2 emissions globally in 2050,
consistent with a temperature rise in 2100 of around 2.1 °C (with a 50% probability).
In this chapter, we examine the energy sector transformation which is embodied in our
Net‐Zero Emissions by 2050 Scenario. First, it provides an overview of the key assumptions
and market dynamics underlying the projections, including projected fossil fuel and CO2
prices. It discusses trends in global CO2 emissions, energy use and investment, including the
key roles played by efficiency measures, behavioural change, electrification, renewables,
hydrogen and hydrogen‐based fuels, bioenergy, and carbon capture, utilisation and storage
(CCUS). Further, it discusses some of the key uncertainties surrounding the global pathway
towards net‐zero emissions related to behavioural change, the availability of sustainable
bioenergy, and the deployment of CCUS for fossil fuels. The transformation of specific energy
sectors is assessed and discussed in detail in Chapter 3.
2.2 Scenario design
The Net‐Zero Emissions by 2050 Scenario (NZE) is designed to show what is needed across
the main sectors by various actors, and by when, for the world to achieve net‐zero energy‐
related and industrial process CO2 emissions by 2050.1 It also aims to minimise methane
emissions from the energy sector. In recent years, the energy sector was responsible for
around three‐quarters of global greenhouse gas (GHG) emissions. Achieving net‐zero energy‐
related and industrial process CO2 emissions by 2050 in the NZE does not rely on action in
areas other than the energy sector, but limiting climate change does require such action. We
therefore additionally examine the reductions in CO2 emissions from land use that would be
commensurate with the transformation of the energy sector in the NZE, working in
co‐operation with the International Institute for Applied Systems Analysis (IIASA). In parallel
with action on reducing all other sources of GHG emissions, achieving net‐zero CO2 emissions
from the energy sector by 2050 is consistent with around a 50% chance of limiting the long‐
term average global temperature rise to 1.5 °C without a temperature overshoot
(IPCC, 2018).
1 Unless otherwise stated, carbon dioxide (CO2) emissions in this chapter refer to energy‐related and industrial
process CO2 emissions. Net‐zero CO2 emissions refers to zero CO2 emissions to the atmosphere, or with any residual CO2 emissions offset by CO2 removal from direct air capture or bioenergy with carbon capture and
storage.
Chapter 2 | A global pathway to net-zero CO₂ emissions in 2050 49
2
The NZE aims to ensure that energy‐related and industrial process CO2 emissions to 2030 are
in line with reductions in 1.5 °C scenarios with no or low or limited temperature overshoot
assessed in the IPCC in its Special Report on Global Warming of 1.5 °C.2 In addition, the NZE
incorporates concrete action on the energy‐related United Nations Sustainable Development
Goals related to achieving universal energy access by 2030 and delivering a major reduction
in air pollution. The projections in the NZE were generated by a hybrid model that combines
components of the IEA’s World Energy Model (WEM), which is used to produce the
projections in the annual World Energy Outlook, and the Energy Technology Perspectives
(ETP) model.
Box 2.1 ⊳ International Energy Agency modelling approach for the NZE
A new, hybrid modelling approach was adopted to develop the NZE and combines the
relative strengths of the WEM and the ETP model. The WEM is a large‐scale simulation
model designed to replicate how competitive energy markets function and to examine
the implications of policies on a detailed sector‐by‐sector and region‐by‐region basis. The
ETP model is a large‐scale partial‐optimisation model with detailed technology
descriptions of more than 800 individual technologies across the energy conversion,
industry, transport and buildings sectors.
This is the first time this modelling approach has been implemented. The combination of
the two models allows for a unique set of insights on energy markets, investment,
technologies, and the level and detail of policies that would be needed to bring about the
energy sector transformation in the NZE.
Results from the WEM and ETP model have been coupled with the Greenhouse Gas ‐ Air
Pollution Interactions and Synergies (GAINS) model developed by IIASA
(Amann et al., 2011). The GAINS model is used to evaluate air pollutant emissions and
resultant health impacts linked to air pollution. For the first time, IEA model results have
also been coupled with the IIASA’s Global Biosphere Management Model (GLOBIOM) to
provide data on land use and net emissions impacts of bioenergy demand.
The impacts of changes in investment and spending on global GDP in the NZE have been
estimated by the International Monetary Fund (IMF) using the Global Integrated
Monetary and Fiscal (GIMF) model. GIMF is a multi‐country dynamic stochastic general
equilibrium model used by the IMF for policy and risk analysis (Laxton et al., 2010;
Anderson et al., 2013). It has been used to produce the IMF’s World Economic Outlook
scenario analyses since 2008.
There are many possible paths to achieve net‐zero CO2 emissions globally by 2050 and many
uncertainties that could affect any of them; the NZE is therefore a path, not the path to net‐
zero emissions. Much depends, for example, on the pace of innovation in new and emerging
2 The IPCC classifies scenarios as “no or limited temperature overshoot”, if temperatures exceed 1.5 °C by less than 0.1 °C but return to less than 1.5 °C in 2100, and as “higher overshoot”, if temperatures exceed 1.5 °C by
0.1‐0.4 °C but return to less than 1.5 °C in 2100.
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technologies, the extent to which citizens are able or willing to change behaviour, the
availability of sustainable bioenergy and the extent and effectiveness of international
collaboration. We investigate some of the key alternatives and uncertainties here and in
Chapter 3. The Net‐Zero Emissions by 2050 Scenario is built on the following principles.
The uptake of all the available technologies and emissions reduction options is dictated
by costs, technology maturity, policy preferences, and market and country conditions.
All countries co‐operate towards achieving net‐zero emissions worldwide. This involves
all countries participating in efforts to meet the net zero goal, working together in an
effective and mutually beneficial way, and recognising the different stages of economic
development of countries and regions, and the importance of ensuring a just transition.
An orderly transition across the energy sector. This includes ensuring the security of fuel
and electricity supplies at all times, minimising stranded assets where possible and
aiming to avoid volatility in energy markets.
2.2.1 Population and GDP
The energy sector transformation in the NZE occurs against the backdrop of large increases
in the world’s population and economy (Figure 2.1). In 2020, there were around 7.8 billion
people in the world; this is projected to increase by around 750 million by 2030 and by nearly
2 billion people by 2050 in line with the median variant of the United Nations projections
(UNDESA, 2019). Nearly all of the population increase is in emerging market and developing
economies: the population of Africa alone increases by more than 1.1 billion between 2020
and 2050.
Figure 2.1 ⊳ World population by region and global GDP in the NZE
IEA. All rights reserved.
By 2050, the world’s population expands to 9.7 billion people and the global economy is more than twice as large as in 2020
Notes: GDP = gross domestic product in purchasing power parity; C & S America = Central and South America.
Sources: IEA analysis based on UNDESA (2019); Oxford Economics (2020); IMF (2020a, 2020b).
100
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400
500
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2000 2010 2020 2030 2040 2050
Trillion USD
(2019)
Billion people Rest of world
EurasiaMiddle EastNorth AmericaC & S AmericaSoutheast AsiaEuropeAfricaIndiaChina
Global GDP(right axis)
Chapter 2 | A global pathway to net-zero CO₂ emissions in 2050 51
2
The world’s economy is assumed to recover rapidly from the impact of the Covid‐19
pandemic. Its size returns to pre‐crisis levels in 2021. From 2022, the GDP growth trend is
close to the pre‐pandemic rate of around 3% per year on average, in line with assessments
from the IMF. The response to the pandemic leads to a large increase in government debt,
but resumed growth, along with low interest rates in many countries, make this manageable
in the long term. By 2030, the world’s economy is around 45% larger than in 2020, and by
2050 it is more than twice as large.
2.2.2 Energy and CO2 prices
Projections of future energy prices are inevitably subject to a high degree of uncertainty. In
IEA scenarios, they are designed to maintain an equilibrium between supply and demand.
The rapid drop in oil and natural gas demand in the NZE means that no fossil fuel exploration
is required and no new oil and natural gas fields are required beyond those that have already
been approved for development. No new coal mines or mine extensions are required either.
Prices are increasingly set by the operating costs of the marginal project required to meet
demand, and this results in significantly lower fossil fuel prices than in recent years. The oil
price drops to around USD 35/barrel by 2030 and then drifts down slowly towards
USD 25/barrel in 2050.
Table 2.1 ⊳ Fossil fuel prices in the NZE
Real terms (USD 2019) 2010 2020 2030 2040 2050
IEA crude oil (USD/barrel) 91 37 35 28 24
Natural gas (USD/MBtu)
United States 5.1 2.1 1.9 2.0 2.0
European Union 8.7 2.0 3.8 3.8 3.5
China 7.8 5.7 5.2 4.8 4.6
Japan 12.9 5.7 4.4 4.2 4.1
Steam coal (USD/tonne)
United States 60 45 24 24 22
European Union 108 56 51 48 43
Japan 125 75 57 53 49
Coastal China 135 81 60 54 50
Notes: MBtu = million British thermal units. The IEA crude oil prices are a weighted average import price among
IEA member countries. Natural gas prices are weighted averages expressed on a gross calorific‐value basis. US
natural gas prices reflect the wholesale price prevailing on the domestic market. The European Union and China gas prices reflect a balance of pipeline and liquefied natural gas (LNG) imports, while Japan gas prices
solely reflect LNG imports. LNG prices used are those at the customs border, prior to regasification. Steam
coal prices are weighted averages adjusted to 6 000 kilocalories per kilogramme. US steam coal prices reflect mine‐mouth price plus transport and handling cost. Coastal China steam coal price reflects a balance of
imports and domestic sales, while the European Union and Japanese steam coal prices are solely for imports.
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In line with the principle of orderly transitions governing the NZE, the trajectory for oil
markets and prices avoids excessive volatility. What happens depends to a large degree on
the strategies adopted by resource‐rich governments and their national oil companies. In the
NZE it is assumed that, despite having lower cost resources at their disposal, they restrict
investment in new fields. This limits the need for the shutting in and closure of higher cost
production. The market share of major resource‐rich countries nevertheless still rises in the
NZE due to the large size and slow decline rates of their existing fields.
Producer economies could pursue alternative approaches. Faced with rapidly falling oil and
gas demand, they could, for example, opt to increase production so as to capture an even
larger share of the market. In this event, the combination of falling demand and increased
availability of low cost oil would undoubtedly lead to even lower – and probably much more
volatile – prices. In practice, the options open to particular producer countries would depend
on their resilience to lower oil prices and on the extent to which export markets have
developed for low‐emissions fuels that could be produced from their natural resources.
Anticipating and mitigating feedbacks from the supply side is a central element of the
discussion about orderly energy transitions. A drop in prices usually results in some rebound
in demand, and policies and regulations would be essential to avoid this leading to any
increase in the unabated use of fossil fuels, which would undermine wider emissions
reduction efforts.
As the energy sector transforms, more fuels are traded globally, such as hydrogen‐based
fuels and biofuels. The prices of these commodities are assumed to be set by the marginal
cost of domestic production or imports within each region.
A broad range of energy policies and accompanying measures are introduced across all
regions to reduce emissions in the NZE. This includes: renewable fuel mandates; efficiency
standards; market reforms; research, development and deployment; and the elimination of
inefficient fossil fuel subsidies. Direct emissions reduction regulations are also needed in
some cases. In the transport sector, for example, regulations are implemented to reduce
sales of internal combustion engine vehicles and increase the use of liquid biofuels and
synthetic fuels in aviation and shipping, as well as measures to ensure that low oil prices do
not lead to an increase in consumption.
CO2 prices are introduced across all regions in the NZE (Table 2.2). They are assumed to be
introduced in the immediate future across all advanced economies for the electricity
generation, industry and energy production sectors, and to rise on average to USD 130 per
tonne (tCO2) by 2030 and to USD 250/tCO2 by 2050. In a number of other major economies
– including China, Brazil, Russia and South Africa – CO2 prices in these sectors are assumed
to rise to around USD 200/tCO2 in 2050. CO2 prices are introduced in all other emerging
market and developing economies, although it is assumed that they pursue more direct
policies to adapt and transform their energy systems and so the level of CO2 prices is lower
than elsewhere.
Chapter 2 | A global pathway to net-zero CO₂ emissions in 2050 53
2
Table 2.2 ⊳ CO2 prices for electricity, industry and energy production in the NZE
USD (2019) per tonne of CO2 2025 2030 2040 2050
Advanced economies 75 130 205 250
Selected emerging market and developing economies*
45 90 160 200
Other emerging market and developing economies
3 15 35 55
* Includes China, Russia, Brazil and South Africa.
2.3 CO2 emissions
Global energy‐related and industrial process CO2 emissions in the NZE fall to around
21 Gt CO2 in 2030 and to net‐zero in 2050 (Figure 2.2).3 CO2 emissions in advanced economies
as a whole fall to net zero by around 2045 and these countries collectively remove around
0.2 Gt CO2 from the atmosphere in 2050. Emissions in several individual emerging market
and developing economies also fall to net zero well before 2050, but in aggregate there are
around 0.2 Gt CO2 of remaining emissions in this group of countries in 2050. These are offset
by CO2 removal in advanced economies to provide net‐zero CO2 emissions at the global level.
Figure 2.2 ⊳ Global net CO2 emissions in the NZE
IEA. All rights reserved.
CO2 emissions fall to net zero in advanced economies around 2045 and globally by 2050. Per capita emissions globally are similar by the early-2040s.
Note: Includes CO2 emissions from international aviation and shipping.
3 In the period to 2030, CO2 emissions in the NZE fall at a broadly similar rate to the P2 illustrative pathway in the IPCC SR 1.5 (IPCC, 2018). The P2 scenario is described as “a scenario with … shifts towards sustainable and
healthy consumption patterns, low‐carbon technology innovation, and well‐managed land systems with
limited societal acceptability for BECCS [bioenergy with carbon capture and storage]”. After 2030, emissions in the NZE fall at a much faster pace than in the P2 scenario, which has 5.6 Gt CO2 of residual energy sector
and industrial process CO2 emissions remaining in 2050.
‐10
0
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30
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2010 2020 2030 2040 2050
Gt CO₂
Advanced economies Emerging market and developing economies
CO₂ emissions
‐3
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2010 2020 2030 2040 2050
tCO₂ per cap
ita
Per capita CO₂ emissions
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Several emerging market and developing economies with a very large potential for producing
renewables‐based electricity and bioenergy are also a key source of carbon dioxide removal
(CDR). This includes making use of renewable electricity sources to produce large quantities
of biofuels with CCUS, some of which is exported, and to carry out direct air capture with
carbon capture and storage (DACCS).
Per capita CO2 emissions in advanced economies drop from around 8 tCO2 per person in 2020
to around 3.5 tCO2 in 2030, a level close to the average in emerging market and developing
economies in 2020. Per capita emissions also fall in emerging market and developing
economies, but from a much lower starting point. By the early 2040s, per capita emissions in
both regions are broadly similar at around 0.5 tCO2 per person.
Cumulative global energy‐related and industrial process CO2 emissions between 2020 and
2050 amount to just over 460 Gt in the NZE. Assuming parallel action to address CO2
emissions from agriculture, forestry and other land use (AFOLU) over the period to 2050
would result in around 40 Gt CO2 from AFOLU (see section 2.7.2). This means that total CO2
emissions from all sources – some 500 Gt CO2 – are in line with the CO2 budgets included in
the IPCC SR1.5, which indicated that the total CO2 budget from 2020 consistent with
providing a 50% chance of limiting warming to 1.5 °C is 500 Gt CO2 (IPCC, 2018).4 As well as
reducing CO2 emissions to net‐zero, the NZE seeks to reduce non‐CO2 emissions from the
energy sector. Methane emissions from fossil fuel production and use, for example, fall from
115 million tonnes (Mt) methane in 2020 (3.5 Gt CO2‐equivalent [CO2‐eq])5 to 30 Mt in 2030
and 10 Mt in 2050.
The fastest and largest reductions in global emissions in the NZE are initially seen in the
electricity sector (Figure 2.3). Electricity generation was the largest source of emissions in
2020, but emissions drop by nearly 60% in the period to 2030, mainly due to major reductions
from coal‐fired power plants, and the electricity sector becomes a small net negative source
of emissions around 2040. Emissions from the buildings sector fall by 40% between 2020 and
2030 thanks to a shift away from the use of fossil fuel boilers, and retrofitting the existing
building stock to improve its energy performance. Emissions from industry and transport
both fall by around 20% over this period, and their pace of emissions reductions accelerates
during the 2030s as the roll‐out of low‐emissions fuels and other emissions reduction options
is scaled up. Nonetheless, there are a number of areas in transport and industry in which it
is difficult to eliminate emissions entirely – such as aviation and heavy industry – and both
sectors have a small level of residual emissions in 2050. These residual emissions are offset
with applications of BECCS and DACCS.
4 This budget is based on Table 2.2 of the IPCC SR1.5 (IPCC, 2018). It assumes 0.53 °C additional warming from
the 2006‐2015 period to give a remaining CO2 budget from 2018 of 580 Gt CO2. There were around 80 Gt CO2
emissions emitted from 2018 to 2020. 5 Non‐CO2 gases are converted to CO2‐equivalents based on the 100‐year global warming potentials reported
by the IPCC 5th Assessment Report (IPCC, 2014). One tonne of methane is equivalent to 30 tonnes of CO2.
Chapter 2 | A global pathway to net-zero CO₂ emissions in 2050 55
2
Figure 2.3 ⊳ Global net-CO2 emissions by sector, and gross and net CO2 emissions in the NZE
IEA. All rights reserved.
Emissions from electricity fall fastest, with declines in industry and transport accelerating in the 2030s. Around 1.9 Gt CO2 are removed in 2050 via BECCS and DACCS.
Notes: Other = agriculture, fuel production, transformation and related process emissions, and direct air
capture. BECCS = bioenergy with carbon capture and storage; DACCS = direct air capture with carbon capture
and storage. BECCS and DACCS includes CO2 emissions captured and permanently stored.
The NZE includes a systematic preference for all new assets and infrastructure to be as
sustainable and efficient as possible, and this accounts for 50% of total emissions reductions
in 2050. Tackling emissions from existing infrastructure accounts for another 35% of
reductions in 2050, while behavioural changes and avoided demand, including materials
efficiency6 gains and modal shifts in the transport sector, provide the remaining 15% of
emissions reductions (see section 2.5.2). A wide range of technologies and measures are
deployed in the NZE to reduce emissions from existing infrastructure such as power plants,
industrial facilities, buildings, networks, equipment and appliances. The NZE is designed to
minimise stranded capital where possible, i.e. cases where the initial investment is not
recouped, but in many cases early retirements or lower utilisation lead to stranded value, i.e.
a reduction in revenue.
The rapid deployment of more energy‐efficient technologies, electrification of end‐uses and
swift growth of renewables all play a central part in reducing emissions across all sectors in
the NZE (Figure 2.4). By 2050, nearly 90% of all electricity generation is from renewables, as
is around 25% of non‐electric energy use in industry and buildings. There is also a major role
for emerging fuels and technologies, notably hydrogen and hydrogen‐based fuels, bioenergy
and CCUS, especially in sectors where emissions are often most challenging to reduce.
6 Materials efficiency includes strategies that reduce material demand, or shift to the use of lower emissions
materials or lower emissions production routes. Examples include lightweighting and recycling.
‐5
0
5
10
15
2010 2020 2030 2040 2050
Gt CO₂ Electricity
Buildings
Transport
Industry
Other
Sector
‐10
0
10
20
30
40
2010 2020 2030 2040 2050
Gross CO₂ emissions
BECCS andDACCS
Net CO₂ emissions
Gross and net CO₂ emissions
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Figure 2.4 ⊳ Average annual CO2 reductions from 2020 in the NZE
IEA. All rights reserved.
Renewables and electrification make the largest contribution to emissions reductions, but a wide range of measures and technologies are needed to achieve net-zero emissions
Notes: Activity = changes in energy service demand from economic and population growth.
Behaviour = change in energy service demand from user decisions, e.g. changing heating temperatures. Avoided demand = change in energy service demand from technology developments, e.g. digitalisation.
2.4 Total energy supply and final energy consumption
2.4.1 Total energy supply7
Total energy supply falls to 550 exajoules (EJ) in 2030, 7% lower than in 2020 (Figure 2.5).
This occurs despite significant increases in the global population and economy because of a
fall in energy intensity (the amount of energy used to generate a unit of GDP). Energy
intensity falls by 4% on average each year between 2020 and 2030. This is achieved through
a combination of electrification, a push to pursue all energy and materials efficiency
opportunities, behavioural changes that reduce demand for energy services, and a major
shift away from the traditional use of bioenergy.8 This level of improvement in energy
intensity is much greater than has been achieved in recent years: between 2010 and 2020,
average annual energy intensity fell by less then 2% each year.
After 2030, continuing electrification of end‐use sectors helps to reduce energy intensity
further, but the emphasis on maximising energy efficiency improvements in the years up to
7 The terms total primary energy supply (TPES) or total primary energy demand (TPED) have been renamed as total energy supply (TES) in accordance with the International Recommendations for Energy Statistics
(IEA, 2020a).
8 Modern forms of cooking require much less energy than the traditional use of biomass in inefficient stoves. For example, cooking with a liquefied petroleum gas stove uses around five‐times less energy than the
traditional use of biomass.
‐60
‐40
‐20
0
20
2021‐25 2026‐30 2031‐35 2036‐40 2041‐45 2046‐50
Gt CO
2 ActivityBehaviour and avoided demandEnergy supply efficiencyBuildings efficiencyIndustry efficiencyTransport efficiencyElectric vehiclesOther electrificationHydrogenWind and solarTransport biofuelsOther renewablesOther powerCCUS industryCCUS power and fuel supply
Net emissions reduction
Chapter 2 | A global pathway to net-zero CO₂ emissions in 2050 57
2
2030 limits the available opportunities in later years. At the same time, increasing production
of new fuels, such as advanced biofuels, hydrogen and synthetic fuels, tends to push up
energy use. As a result, the rate of decline in energy intensity between 2030 and 2050 slows
to 2.7% per year. With continued economic and population growth, this means that total
energy supply falls slightly between 2030 and 2040 but then remains broadly flat to 2050.
Total energy supply in 2050 in the NZE is close to the level in 2010, despite a global population
that is nearly 3 billion people higher and a global economy that is over three‐times larger.
Figure 2.5 ⊳ Total energy supply in the NZE
IEA. All rights reserved.
Renewables and nuclear power displace most fossil fuel use in the NZE, and the share of fossil fuels falls from 80% in 2020 to just over 20% in 2050
The energy mix in 2050 in the NZE is much more diverse than today. In 2020, oil provided
30% of total energy supply, while coal supplied 26% and natural gas 23%. In 2050, renewables
provide two‐thirds of energy use, split between bioenergy, wind, solar, hydroelectricity and
geothermal (Figure 2.6). There is also a large increase in energy supply from nuclear power,
which nearly doubles between 2020 and 2050.
There are large reductions in the use of fossil fuels in the NZE. As a share of total energy
supply, they fall from 80% in 2020 to just over 20% in 2050. However, their use does not fall
to zero in 2050: significant amounts are still used in producing non‐energy goods, in plants
with CCUS, and in sectors where emissions are especially hard to abate such as heavy
industry and long‐distance transport. All remaining emissions in 2050 are offset by negative
emissions elsewhere (Box 2.2). Coal use falls from 5 250 million tonnes of coal equivalent
(Mtce) in 2020 to 2 500 Mtce in 2030 and to less than 600 Mtce in 2050 – an average annual
decline of 7% each year from 2020 to 2050. Oil demand dropped below 90 million barrels
per day (mb/d) in 2020 and demand does not return to its 2019 peak: it falls to 72 mb/d in
2030 and 24 mb/d in 2050 – an annual average decline of more than 4% from 2020 to 2050.
Natural gas use dropped to 3 900 billion cubic metres (bcm) in 2020, but exceeds its previous
100
200
300
400
500
600
2000 2010 2020 2030 2040 2050
EJ OtherOther renewablesWindSolarHydroTraditional use of biomassModern gaseous bioenergyModern liquid bioenergyModern solid bioenergyNuclearNatural gasOilCoal
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2019 peak in the mid‐2020s before starting to decline as it is phased out in the electricity
sector. Natural gas use declines to 3 700 bcm in 2030 and 1 750 bcm in 2050 – an annual
average decline of just under 3% from 2020 to 2050.
Figure 2.6 ⊳ Total energy supply of unabated fossil fuels and low-emissions energy sources in the NZE
IEA. All rights reserved.
Some fossil fuels are still used in 2050 in the production of non-energy goods, in plants equipped with CCUS, and in sectors where emissions are hard to abate
Note: Low‐emissions includes the use of fossil fuels with CCUS and in non‐energy uses.
Box 2.2 ⊳ Why does fossil fuel use not fall to zero in 2050 in the NZE?
In total, around 120 EJ of fossil fuels is consumed in 2050 in the NZE relative to 460 EJ in
2020. Three main reasons underlie why fossil fuel use does not fall to zero in 2050, even
though the energy sector emits no CO2 on a net basis:
Use for non‐energy purposes. More than 30% of total fossil fuel use in 2050 in the
NZE – including 70% of oil use – is in applications where the fuels are not combusted
and so do not result in any direct CO2 emissions (Figure 2.7). Examples include use
as chemical feedstocks and in lubricants, paraffin waxes and asphalt. There are
major efforts to limit fossil fuel use in these applications in the NZE, for instance
global plastic collection rates for recycling rising from 15% in 2020 to 55% in 2050,
but fossil fuel use in non‐energy applications still rises slightly to 2050.
Use with CCUS. Around half of fossil fuel use in 2050 is in plants equipped with CCUS
(around 3.5 Gt CO2 emissions are captured from fossil fuels in 2050). Around
925 bcm of natural gas is converted to hydrogen with CCUS. In addition, around
470 Mtce of coal and 225 bcm of natural gas are used with CCUS in the electricity
and industrial sectors, mainly to extend the operations of young facilities and reduce
stranded assets.
100
200
300
400
500
600
2010 2020 2030 2040 2050 2010 2020 2030 2040 2050
EJ OtherrenewablesSolarWindTraditionaluse of biomassModernbioenergyHydroNuclearNatural gasOilCoal
Unabated fossil fuels Low‐emissions
Chapter 2 | A global pathway to net-zero CO₂ emissions in 2050 59
2
Use in sectors where technology options are scarce. The remaining 20% of fossil
fuel use in 2050 in the NZE is in sectors where the complete elimination of emissions
is particularly challenging. Mostly this is oil, as it continues to fuel aviation in
particular. A small amount of unabated coal and natural gas are used in industry and
in the production of energy. The unabated use of fossil fuel results in around
1.7 Gt CO2 emissions in 2050, which are fully offset by BECCS and DACCS.
Figure 2.7 ⊳ Fossil fuel use and share by sector in 2050 in the NZE
IEA. All rights reserved.
More than 30% of fossil fuel use in 2050 is not combusted and so does not result in direct CO2 emissions, around 50% is paired with CCUS
Notes: Non‐combustion includes use for non‐emitting, non‐energy purposes such as petrochemical
feedstocks, lubricants and asphalt. Energy production includes fuel use for direct air capture.
Solid, liquid and gaseous fuels continue to play an important role in the NZE, which sees large
increases in bioenergy and hydrogen (Figure 2.8). Around 40% of bioenergy used today is for
the traditional use of biomass in cooking: this is rapidly phased out in the NZE. Modern forms
of solid biomass, which can be used to reduce emissions in both the electricity and industry
sectors, rise from 32 EJ in 2020 to 55 EJ in 2030 and 75 EJ in 2050, offsetting a large portion
of a drop in coal demand. The use of low‐emissions liquid fuels, such as ammonia, synthetic
fuels and liquid biofuels, increases from 3.5 EJ (1.6 million barrels of oil equivalent per day
[mboe/d]) in 2020 to just above 25 EJ (12.5 mboe/d) in 2050. The supply of low‐emissions
gases, such as hydrogen, synthetic methane, biogas and biomethane rises from 2 EJ in 2020
to 17 EJ in 2030 and 50 EJ in 2050. The increase in gaseous hydrogen production between
2020 and 2030 in the NZE is twice as fast as the fastest ten‐year increase in shale gas
production in the United States.
20%
40%
60%
80%
100%
10
20
30
40
50
Non‐
combustion
Energy
production
Industry
Power
Tran
sport
Build
ings
EJ
with CCUS
without CCUS
with CCUS
without CCUS
with CCUS
without CCUS
Share of sector
Coal
Natural gas
Oil
total (right axis)
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Figure 2.8 ⊳ Solid, liquid and gaseous fuels in the NZE
IEA. All rights reserved.
Increases in low-emissions solids, liquids and gases from bioenergy, hydrogen and hydrogen-based fuels offset some of the declines in coal, oil and natural gas
Notes: Hydrogen conversion losses = consumption of natural gas when producing low‐carbon merchant hydrogen using steam methane reforming. Hydrogen‐based includes hydrogen, ammonia and synthetic fuels.
2.4.2 Total final consumption
Total final consumption worldwide rebounds marginally following its 5% drop in 2020, but it
never returns to 2019 levels in the NZE (435 EJ). It falls by just under 1% each year on average
between 2025 and 2050 to 340 EJ. Energy efficiency measures and electrification are the two
main contributing factors, with behavioural changes and materials efficiency also playing a
role. Without these improvements, final energy consumption in 2050 would be around
640 EJ, around 90% higher than the level in the NZE. Final consumption of electricity
increases by 25% from 2020 to 2030, and by 2050 it is more than double the level in 2020.
The increase in electricity consumption from end‐uses sectors and from hydrogen production
means that overall annual electricity demand growth is equivalent to adding an electricity
market the size of India every year in the NZE. The share of electricity in global final energy
consumption jumps from 20% in 2020 to 26% in 2030 and to around 50% in 2050 (Figure 2.9).
The direct use of renewables in buildings and industry together with low‐emissions fuels such
as bioenergy and hydrogen‐based fuels provide a further 28% of final energy consumption
in 2050; fossil fuels comprise the remainder, most of which are used in non‐emitting
processes or in facilities equipped with CCUS.
In industry, most of the global emissions reductions in the NZE during the period to 2030 are
delivered through energy and materials efficiency improvements, electrification of heat, and
fuel switching to solar thermal, geothermal and bioenergy. Thereafter, CCUS and hydrogen
play an increasingly important role in reducing CO2 emissions, especially in heavy industries
such as steel, cement and chemicals. Electricity consumption in industry more than doubles
between 2020 and 2050, providing 45% of total industrial energy needs in 2050 (Figure 2.10).
50
100
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2020
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2050
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2000
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EJ
Coal Oil Natural gas Hydrogen conversionTraditional biomass Modern bioenergy Hydrogen‐based
Solids Liquids Gases
losses
Chapter 2 | A global pathway to net-zero CO₂ emissions in 2050 61
2
The demand for merchant hydrogen in industry increases from less than 1 Mt today to
around 40 Mt in 2050. A further 10% of industrial energy demand in 2050 is met by fossil
fuels used in plants equipped with CCUS.
Figure 2.9 ⊳ Global total final consumption by fuel in the NZE
IEA. All rights reserved.
The share of electricity in final energy use jumps from 20% in 2020 to 50% in 2050
Note: Hydrogen‐based includes hydrogen, ammonia and synthetic fuels.
In transport, there is a rapid transition away from oil worldwide, which provided more than
90% of fuel use in 2020. In road transport, electricity comes to dominate the sector, providing
more than 60% of energy use in 2050, while hydrogen and hydrogen‐based fuels play a
smaller role, mainly in fuelling long‐haul heavy‐duty trucks. In shipping, energy efficiency
improvements significantly reduce energy needs (especially up to 2030), while advanced
biofuels and hydrogen‐based fuels, such as ammonia, increasingly displace oil. In aviation,
the use of synthetic liquids and advanced biofuels grows rapidly, and their share of total
energy demand rises from almost zero today to almost 80% in 2050. Overall, electricity
becomes the dominant fuel in the transport sector globally by the early 2040s, and it
accounts for around 45% of energy consumption in the sector in 2050 (compared with 1.5%
in 2020). Hydrogen and hydrogen‐based fuels account for nearly 30% of consumption
(almost zero in 2020) and bioenergy for a further 15% (around 4% in 2020).
In buildings, the electrification of end‐uses including heating leads to demand for electricity
increasing by around 35% between 2020 and 2050: it becomes the dominant fuel, reaching
16 000 terawatt‐hours (TWh) in 2050, and accounting for two‐thirds of total buildings sector
energy consumption. By 2050, two‐thirds of residential buildings in advanced economies and
around 40% of residential buildings in emerging market and developing economies are fitted
with a heat pump. Onsite renewables‐based energy systems such as solar water heaters and
biomass boilers provide a further quarter of final energy use in the buildings sector in 2050
(up from 6% in 2020). Low‐emissions district heating and hydrogen provide only 7% of energy
use, but play a significant role in some regions.
50 100 150 200 250 300 350
2010
2020
2030
2040
2050
2010
2020
2030
2040
2050
EJ
OilNatural gasCoalHeatModern bioenergyTraditional useof biomassHydrogen‐basedOther renewables
Fossil fuels unabatedFossil fuels with CCUSHydrogen‐basedNuclearSolar PV and windHydroOther renewables
Fuels and other
Electricity use
Fuels an
d other
Electricity use
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Figure 2.10 ⊳ Global final energy consumption by sector and fuel in the NZE
IEA. All rights reserved.
There is a wholesale shift away from unabated fossil fuel use to electricity, renewables, hydrogen and hydrogen-based fuels, modern bioenergy and CCUS in end-use sectors
Note: Hydrogen‐based includes hydrogen, ammonia and synthetic fuels.
Buildings energy consumption falls by 25% between 2020 and 2030, largely as a result of a
major push to improve efficiency and to phase out the traditional use of solid biomass for
cooking: it is replaced by liquefied petroleum gas (LPG), biogas, electric cookers and
improved bioenergy stoves. Universal access to electricity is achieved by 2030, and this adds
less than 1% to global electricity demand in 2030. Energy consumption in the buildings sector
contracts by around 15% between 2030 and 2050 given continued efficiency improvements
and electrification. By 2050, energy use in buildings is 35% lower than in 2020. Energy
efficiency measures – including improving building envelopes and ensuring that all new
appliances brought to market are the most efficient models available – play a key role in
limiting the rise in electricity demand in the NZE. Without these measures, electricity
demand in buildings would be around 10 000 TWh higher in 2050, or around 70% higher than
the level in the NZE.
How does the NZE compare with similar 1.5 °C scenarios assessed by the IPCC?
The IPCC SR1.5 includes 90 individual scenarios that have at least a 50% chance of limiting
warming in 2100 to 1.5 °C (IPCC, 2018).9 Only 18 of these scenarios have net‐zero CO2
energy sector and industrial process emissions in 2050. In other words, only one‐in‐five
of the 1.5 °C scenarios assessed by the IPCC have the same level of emissions reduction
9 Includes 53 scenarios with no or limited temperature overshoot and 37 scenarios with a higher temperature
overshoot.
40
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200
2010
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2010
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EJ OtherHydrogen‐basedOther renewablesModern bioenergyTraditional useof biomassElectricityFossil fuels with CCUSUnabated fossil fuels
Industry Transport Buildings
S P O T L I G H T
Chapter 2 | A global pathway to net-zero CO₂ emissions in 2050 63
2
ambition for the energy and industrial process sectors to 2050 as the NZE.10 Some
comparisons between these 18 scenarios and the NZE in 2050 (Figure 2.11):
Figure 2.11 ⊳ Comparison of selected indicators of the IPCC scenarios and the NZE in 2050
IEA. All rights reserved.
The NZE has the lowest level of energy-related CDR and bioenergy of any scenario that achieves net-zero energy sector and industrial process CO2 emissions in 2050
Notes: CCUS = carbon capture, utilisation and storage; CDR = carbon direct removal; TES = total energy
supply; TFC = total final consumption. Energy‐related CDR includes CO2 captured through bioenergy with CCUS and direct air capture with CCUS and put into permanent storage. Wind and solar share are given
as a percentage of total electricity generation. Only 17 of the 18 scenarios assessed by the IPCC report
hydrogen use in TFC.
Use of CCUS. The scenarios assessed by the IPCC have a median of around 15 Gt CO2
captured using CCUS in 2050, more than double the level in the NZE.
Use of CDR. CO2 emissions captured and stored from BECCS and DACCS in the IPCC
scenarios range from 3.5‐16 Gt CO2 in 2050, compared with 1.9 Gt CO2 in the NZE.
10 The low‐energy demand scenario has around 4.5 Gt CO2 energy sector and industrial process emissions in
2050 and is not included in this comparison.
10
20
30
40
EJ
Hydrogen in TFC
25%
50%
75%
100%Wind and solar share
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160
240
320
EJ
Bioenergy TES
5
10
15
20
Gt CO
2
CCUS
5
10
15
20
Gt CO₂
Energy‐related CDR
150
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450
600
EJ
Scenarios assessed by IPCC NZE
TFC
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Bioenergy. The IPCC scenarios use a median of 200 EJ of primary bioenergy in 2050
(compared with 63 EJ today) and a number use more than 300 EJ. The NZE uses
100 EJ of primary bioenergy in 2050.
Energy efficiency. Total final consumption in the IPCC scenarios range from
300‐550 EJ in 2050 (compared with around 410 EJ in 2020). The NZE has final energy
consumption of 340 EJ in 2050.
Hydrogen. The IPCC scenarios have a median of 18 EJ hydrogen in total final
consumption in 2050, compared with 33 EJ in the NZE.11
Electricity generation. The shares of wind and solar in total electricity generation in
2050 in the IPCC scenarios range from around 15‐80% with a median value of 50%.
In the NZE, wind and solar provide 70% of total generation in 2050.
2.5 Key pillars of decarbonisation
Achieving the rapid reduction in CO2 emissions over the next 30 years in the NZE requires a
broad range of policy approaches and technologies (Figure 2.12). The key pillars of
decarbonisation of the global energy system are energy efficiency, behavioural changes,
electrification, renewables, hydrogen and hydrogen‐based fuels, bioenergy and CCUS.
Figure 2.12 ⊳ Emissions reductions by mitigation measure in the NZE, 2020-2050
IEA. All rights reserved.
Solar, wind and energy efficiency deliver around half of emissions reductions to 2030 in the NZE, while electrification, CCUS and hydrogen ramp up thereafter
Notes: Activity = energy service demand changes from economic and population growth. Behaviour = energy service demand changes from user decisions, e.g. changing heating temperatures. Avoided demand = energy
service demand changes from technology developments, e.g. digitalisation. Other fuel shifts = switching from
coal and oil to natural gas, nuclear, hydropower, geothermal, concentrating solar power or marine.
11 The NZE value for hydrogen includes the total energy content of hydrogen and hydrogen‐based fuels
consumed in final energy consumption.
15
30
45
2020 2030 2050
Gt CO₂ Activity
Behaviour and
avoided demand
Energy efficiency
Hydrogen‐based
Electrification
Bioenergy
Wind and solar
Other fuel shifts
CCUS
+24%
‐50%
+51%
‐100%
Mitigation measures
Measures
Measures
Chapter 2 | A global pathway to net-zero CO₂ emissions in 2050 65
2
2.5.1 Energy efficiency
Minimising energy demand growth through improvements in energy efficiency makes a
critical contribution in the NZE. Many efficiency measures in industry, buildings, appliances
and transport can be put into effect and scaled up very quickly. As a result, energy efficiency
measures are front‐loaded in the NZE, and they play their largest role in curbing energy
demand and emissions in the period to 2030. Although energy efficiency improves further
after 2030, its contribution to overall emissions reductions falls as other mitigation measures
play an expanding role. Without the energy efficiency, behavioural changes and
electrification measures deployed in the NZE, final energy consumption would be around
300 EJ higher in 2050, almost 90% above the 2050 level in the NZE (Figure 2.13). Efficiency
improvements also help reduce the vulnerability of businesses and consumers to potential
disruptions to electricity supplies.
Figure 2.13 ⊳ Total final consumption and demand avoided by mitigation measure in the NZE
IEA. All rights reserved.
Energy efficiency plays a key role in reducing energy consumption across end-use sectors
Notes: CCUS = carbon capture utilisation and storage. Other fuel switch includes switching to hydrogen‐related
fuels, bioenergy, solar thermal, geothermal, or district heat.
In the buildings sector, many efficiency measures yield financial savings as well as reducing
energy use and emissions. In the NZE, there are immediate and rapid improvements in
energy efficiency in buildings, mainly from large‐scale retrofit programmes. Around 2.5% of
existing residential buildings in advanced economies are retrofitted each year to 2050 in the
NZE to comply with zero‐carbon‐ready building standards12 (compared with a current retrofit
rate of less than 1%). In emerging market and developing economies, building replacement
12 A zero‐carbon‐ready building is highly energy efficient and uses either renewable energy directly or from an
energy supply that will be fully decarbonised by 2050 in the NZE (such as electricity or district heat). A zero‐carbon‐ready building will become a zero‐carbon building by 2050, without further changes to the building or
its equipment (see Chapter 3).
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2020 2030 2050 2020 2030 2050 2020 2030 2050
EJ
NZE demand Electricity Other fuel switch Efficiency Behaviour
Industry Buildings Transport
Avoided due to:
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rates are higher and the annual rate of retrofits is around 2% through to 2050. By 2050, the
vast majority of existing residential buildings are retrofitted to be zero‐carbon buildings.
Energy‐related building codes are introduced in all regions by 2030 to ensure that virtually
all new buildings constructed are zero‐carbon‐ready. Minimum energy performance
standards and replacement schemes for low‐efficiency appliances are introduced or
strengthened in the 2020s in all countries. By the mid‐2030s, nearly all household appliances
sold worldwide are as efficient as the most efficient models available today.
In the transport sector, stringent fuel‐economy standards and ensuring no new
passenger cars running on internal combustion engines (ICEs) are sold globally from 2035
result in a rapid shift in vehicle sales toward much more efficient electric vehicles (EVs).13 The
impact on efficiency is seen in the 2030s, as the composition of the vehicle stock changes:
electric cars make up 20% of all cars on the road in 2030 and 60% in 2040 (compared with
1% today). Continuous improvements in the fuel economy of heavy road vehicles take place
through to 2050 as they switch to electricity or fuel cells, while efficiency in shipping and
aviation improves as more efficient planes and ships replace existing stock.
In the industry sector, most manufacturing stock is already quite efficient, but there are still
opportunities for energy efficiency improvements. Energy management systems,
best‐in‐class industrial equipment such as electric motors, variable speed drives, heaters and
grinders are installed, and process integration options such as waste heat recovery are
exploited to their maximum economic potentials in the period to 2030 in the NZE. After 2030,
the rate of efficiency improvement slows because many of the technologies needed to
reduce emissions in industry in the NZE require more energy than their equivalent
conventional technologies. The use of CCUS, for example, increases energy consumption to
operate the capture equipment, and producing electrolytic hydrogen on‐site requires
additional energy than that needed for the main manufacturing process.
Table 2.3 ⊳ Key global milestones for energy efficiency in the NZE
Sector 2020 2030 2050
Total energy supply 2010‐20 2020‐30 2030‐50
Annual energy intensity improvement (MJ per USD GDP) ‐1.6% ‐4.2% ‐2.7%
Industry
Energy intensity of direct reduced iron from natural gas (GJ per tonne) 12 11 10
Process energy intensity of primary chemicals (GJ per tonne) 17 16 15
Transport
Average fuel consumption of ICE heavy trucks fleet (index 2020=100) 100 81 63
Buildings
Share of zero‐carbon‐ready buildings in total stock <1% 25% >85%
New buildings: heating & cooling energy consumption (index 2020=100) 100 50 20
Appliances: unit energy consumption (index 2020=100) 100 75 60
Notes: ICE = internal combustion engine; zero‐carbon‐ready buildings = see description in section 3.7.
13 In 2020, the average battery electric car required around 30% of the energy of the average ICE car to provide
the same level of activity.
Chapter 2 | A global pathway to net-zero CO₂ emissions in 2050 67
2
2.5.2 Behavioural change
The wholescale transformation of the energy sector demonstrated in the NZE cannot be
achieved without the active and willing participation of citizens. It is ultimately people who
drive demand for energy‐related goods and services, and societal norms and personal
choices will play a pivotal role in steering the energy system onto a sustainable path. Just
under 40% of emissions reductions in the NZE result from the adoption of low‐carbon
technologies that require massive policy support and investment but little direct
engagement from citizens or consumers, e.g. technologies in electricity generation or steel
production. A further 55% of emissions reductions require a mixture of the deployment of
low‐carbon technologies and the active involvement or engagement of citizens and
consumers, e.g. installing a solar water heater or buying an EV. A final 8% of emissions
reductions stem from behavioural changes and materials efficiency gains that reduce energy
demand, e.g. flying less for business purposes (Figure 2.14). Consumer attitudes can also
impact investment decisions by businesses concerned about public image.
In the NZE, behavioural change refers to changes in ongoing or repeated behaviour on the
part of consumers which impact energy service demand or the energy intensity of an energy‐
related activity.14 Reductions in energy service demand in the NZE also come from advances
in technology, but these are not counted as behavioural changes. For example, increased
digitalisation and a growing market share of smart appliances, such as smart thermostats or
space‐differentiated thermal controls reduce the necessity for people to play an active role
in energy saving in homes over time in the NZE.
There are three main types of behavioural change included in the NZE. A wide range of
government interventions could be used to motivate these changes (see section 2.7.1).
Reducing excessive or wasteful energy use. This includes reducing energy use in
buildings and on roads, e.g. by reducing indoor temperature settings, adopting energy
saving practices in homes and limiting driving speeds on motorways to 100 kilometres
per hour.
Transport mode switching. This includes a shift to cycling, walking, ridesharing or taking
buses for trips in cities that would otherwise be made by car, as well as replacing
regional air travel by high‐speed rail in regions where this is feasible. Many of these
types of behavioural changes would represent a break in familiar or habitual ways of life
and as such would require a degree of public acceptance and even enthusiasm. Many
would also require new infrastructure, such as cycle lanes and high‐speed rail networks,
clear policy support and high quality urban planning.
Materials efficiency gains. This includes reduced demand for materials, e.g. higher rates
of recycling, and improved design and construction of buildings and vehicles. The scope
for gains to some extent reflects societal preferences. For instance, in some places there
14 This means, for example, that purchasing an electric heat pump instead of a gas boiler is not considered as a behavioural change, as it is both an infrequent event and does not necessarily impact energy service
demand.
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has been a shift away from the use of single‐use plastics in recent years, a trend that
accelerates in the NZE. Gains in materials efficiency depend on a mixture of technical
innovation in manufacturing and buildings construction, standards and regulations to
support best‐practice and ensure universal adoption of these innovations, and increased
recycling in society at large.
Figure 2.14 ⊳ Role of technology and behavioural change in emissions reductions in the NZE
IEA. All rights reserved.
Around 8% of emissions reductions stem from behavioural changes and materials efficiency
Notes: Low‐carbon technologies include low‐carbon electricity generation, low‐carbon gases in end‐uses and biofuels. Low‐carbon technologies with the active involvement of citizens includes fuel switching,
electrification and efficiency gains in end‐uses. Behavioural changes and materials efficiency includes
transport mode switching, curbing excessive or wasteful energy use, and materials efficiency measures.
Three‐quarters of the emissions reductions from behavioural changes in the NZE are
achieved through targeted government policies supported by infrastructure development,
e.g. a shift to rail travel supported by high‐speed railways. The remainder come from
adopting voluntary changes in energy saving habits, mainly in homes. Even in this case, public
awareness campaigns can help shape day‐to‐day choices about how consumers use energy.
(Details of what governments can do to help bring about behavioural changes are discussed
in Chapter 4).
Behavioural changes reduce energy‐related activity by around 10‐15% on average over the
period to 2050 in the NZE, reducing overall global energy demand by over 37 EJ in 2050
(Figure 2.15). In 2030, around 1.7 Gt CO2 emissions are avoided, 45% of which come from
transport, notably through measures to phase out car use in cities and to improve fuel
economy. For example, reducing speed limits on motorways to 100 km/h reduces emissions
from road transport by 3% or 140 Mt CO2 in 2030. A shift away from single occupancy car use
towards ridesharing or cycling and walking in large cities saves a further 185 Mt CO2. Around
‐35
‐30
‐25
‐20
‐15
‐10
‐5
2020 2030 2040 2050
Gt CO
2 Low‐carbon technologies
Low‐carbon technologies with the active involvement of consumers
Behavioural changesand materials